Hope this helps…
Early Christians and even in the Bible believed that purgatory did exist. There are many references of prayers for the dead in the Catacombs. The references are found on the walls in the form of graffiti written above the graves of the early Christians. Why would there be prayers for the dead if they were already in Heaven? If the deceased were some where other than Heaven or Hell, then they would need prayers. Also, there is no evidence in early writing that there was a struggle with this belief, it was accepted and well known. To this day Orthodox Jews still pray for the souls of their dead friends and relatives. So the notion of Purgatory is far from being an invention of the Catholic faith, it goes back way before Christ.
(Mt. 12-32) - *“And whoever says a word against the Son of man will be forgiven; but whoever speaks against the Holy Spirit will not be forgiven either in this age or in the age to come.” *(Some sins can be forgiven after death-where? Purgatory)
(1 Cor 3:13,15) - "Each man’s work will become manifest; for the Day will disclose it, because it will be revealed with fire, and the fire will test what sort of work each one has done. (15) If any man’s work is burned up, he will suffer loss, though he himself will be saved, but only as through fire." (The fire is the purification of Purgatory).
(1 Peter 3:19-20) - *"…in which he went and preached to the spirits in prison, who formerly did not obey, when God’s patience waited in the days of Noah, during the building of the ark, in which a few, that is, eight persons, were saved through water." *(After Jesus’ death he went and preached to the spirits in prison that were disobedient. Now, these prisoners were not in Heaven or Hell, where were they? These spirits are in a waiting place being purified for their disobedience, the place is called Purgatory.)
(2 Maccabees, 12-46) - “It is therefore a holy and wholesome thought to pray for the dead that they may be loosed from their sins.”